Secret files have revealed that terrorists claim to be hiding a nuclear bomb in Europe, according to WikiLeaks.

An al-Qaeda commander claims that a such a dirty bomb will apparently be detonated if Osama bin Laden is captured or assassinated. The files also reveal only one in three detainees at the Guantanamo Bay detention camp was classed as a dangerous terrorist. About half were foot soldiers and one in five was innocent. The documents, shown to a number of newspapers, detail the interrogations of the 780 people who have passed through the US detention camp in Cuba.

Information that they provided during interrogations is also listed. About 220 of those detained were assessed as dangerous international terrorists, while about 380 are judged to be lower-level troops. At least 150 people were held and assessed but released because of a lack of evidence, according to the files. More than 100 al-Qaeda terrorists are said to have been held at the centre, the most senior being Khalid Sheikh Mohammed.

He is accused of masterminding the 9/11 attacks and faces a military tribunal this year. Sheikh Mohammed’s file is said to state: ‘Detainee had numerous plots and plans for operations targeting the US, its allies, and interests worldwide. ‘Targeting priorities were determined by initially assessing those that would have the greatest economic impact, and secondly which would awaken people politically.’

Sheikh Mohammed is said to have told interrogators al-Qaeda would unleash a ‘nuclear hellstorm’ and planned to recruit staff at Heathrow airport. The Guantanamo Bay centre was opened by the US government four months after the 9/11 attacks and holds about 180 people at present. Torture-style techniques were used there during the Bush administration.